Rotary seam welding transformer



I Filed Jan. 2, 1951 Jan. 12, 1954 ALLARDT 2,666,121

ROTARY SEAM WELDING TRANSFORMER 2 Sheets-Sheet l INVENTOR ATTORNEY Jan. 12, 1954 w, ALLARDT 2,666,121

ROTARY SEAM WELDING TRANSFORMER Filed Jan. 2, 1951 2 Sheets-Sheet 2 INVENTOR ATTORNEY lation between the electrodes.

Patented Jan. 12, 1954 ROTARY SEAM WELDING TRANSFORMER Ernst W. Allardt, Alliance, Ohio, assignor, by mesnc assignments, to The Babcock & Wilcox Company, Jersey City, N. J a corporation of New Jersey Application January 2, 1951, Serial No. 204,029

Claims. (01. 219-6) This invention relates to resistance weldin apparatus, and more particularly to a novel mounting for the welding electrodes of a rotary Welding transformer for resistance welding longitudinal seams, for example, in the manufacture of welded tubing.

In the manufacture of such tubing. an elongated stripof skelp is fed through a series of forming rolls which progressively shape the strip into the form of a tube having an open slit extending longitudinally thereof. The thus formed tubing is then progressively fed into operative relationship with a pair of welding electrodes, each of which engage the tubing an opposite sides of the abutting edges of the seam. A relatively heavy current is passed from one electrode to the other electrode through the abutted edges of the tube, these edges being forced into engagement under pressure by suitable squeeze rolls. The heat created by the resistance to the flow of electric current across the abutted tube edges forms a resistance weld closing the tube.

Various arrangements have been proposed and tried for conducting the relatively heavy electric currents to the rotating welding electrodes. Such arrangements include rotary welding transformers in which the electrodes are secured as a unit to the transformer, or commutator means for conducting current from a stationary transformer to the rotating electrodes.

One of the difficulties encountered with rotatable transformers has been the provision and maintenance of proper relative adjustment of the electrodes in accordance with the desired width of weld. The present invention is directed to a novel rotary welding transformer in which the electrodes are mounted on tapered mounting surfaces on the outer end of a tubular single turn secondary winding. The inner and outer electrodes are bolted together, with a dielectric disk therebetween, to form an electrode unit which is then mounted on the tapered mounting surfaces. The dielectric disk is so chosen as to provide the desired electrical insu- A nut threaded on the outer end of the tubular secondary forces the electrode unit into firm seating engagement on the mounting surfaces.

For a clearer understanding of the invention principles, references is made to the following description of a typical embodiment thereof as illustrated in the accompanying drawings.

In the drawings: Fig. 1 is an axial sectional view through a rotary seam welding transformer embodying the invention;

Figs. 2, 3 and 4 are diametrical sectional views on the correspondingly numbered lines of Fig. 1; and

Figs. 5 and 6 are sectional views on the correspondingly numbered lines of Fig. 2.

Referring to Fig. l, a rotary welding transformer generally indicated at I6 is rotatably supported in a relatively sturdy bracket I l, with the disk welding electrodes l5 and 20 centered relative to a tube 25 fed between squeeze rolls l2, l2. The transformer is supported in bracket I l by an inner roller bearing assembly i3 and an outer roller and thrust bearing assembly 14. A ring i6 on the inner side of bracket ll supports a sealing ring I! in engagement with the inner race l8 of bearing assembly l3. A similar ring 2| secured to the outer face of bracket H maintains a sealing ring 22 in operative relation with the inner race 23 of bearing assembly I4. The bearing assemblies 13 and [4 are maintained in proper position on the transformer by inner and outer end rings 24 and 26 threaded on the transformer ID. The rings or nuts 24, 26 are also used to align the center of the electrodes with the center of the squeeze rolls.

In the particular rotary welding transformer illustrated, the secondary winding comprises a pair of complementary housing sections 21 and 28 of electrically conductive material, which are secured together to form a housing enclosing a toroidal cavity 29 in which are mounted the primary winding 30 and the transformer magneticcore 35. Section 21 has a circumferential recess in which is seated a sprocket gear 3| secured to the section by bolts 32 which unite the two housing sections, insulating sleeves 33 surrounding bolts 32 within gear 3|. The insulation of gear 3| from section 21 is provided by insulation 34 seated in the recess in section 21.

Secondary housing section 21 is secured, in electrically conductive relation, to an inner cylindrical member 36, and section 28 is secured to a cylindrical conductive member 31 telescoped over member 36. An insulating sleeve 38 is disposed between the outer surface of member 31 and the bearing assemblies, and insulation '39 is disposed between the two cylindrical members and between the inner periphery of section 28 and member 36. For a purpose to be described, member 36 has an axial passage ,4! and longitudinally extending passages 42 formed there- .through. Similarly, cylindrical member 3! has longitudinally therethrough. accordance with the invention principles, the outer end of member 36 has a recess thereon receiving a trapazoidal bearing ring 44 having its extending passages 43 formed outer surface sloping at a relatively small angle to the axis of the transformer. This bearing ring serves as a seat for the inner electrode I5. The seat for the outer electrode is formed by a cap 45 which is bolted by studs 4'5 to the inner cylindrical member 36. Cap 45 has passages 41 interconnecting passage M and passages 42. The cap also has a central bore 48, and assages 49 extending therefrom, the bore 48 and passages 49 intei connecting passage M and passages 43.

' through extension BI and passage 4| in member The inner portion of the outer surface of cap; 45 is sloped, as at 5|, so that the surface por tion 5I forms a continuation of the outer surface of ring 44. These two surfaces conjointly. provide a tapered seat mounting for electrodes I5 and 20, with electrode 20 seated on surface.

5|. A clamping ring 52 is threaded on the outer end of cap 45 and serves to force the electrodes I5 and 20 into firmengagement with their tapered seating surfaces.

The electrodes are interconnected by bolt and nut arrangements 53, insulating sleeves 54 electrically insulating electrode 20 from. bolts 53. An insulating disk 55 is disposed between the adjacent electrode surfaces, and the thickness of this disk is selected to provide the desired electrical insulation of the weldingelectrodes.

Circulation of coolant to the transformer elements may be effected through the medium of a manifold generally indicated at 60. This manifold includes an innertubular extension fitting in an axial recess 02 in the end of member 36, and extending through the casing section 21. Insulation 63 insulate extension 6| from member 36 and casing section 21, the manifold being heldto the transformer by suitable studs 64.

Manifold 60 has an annular enlarged portion 65 seated against casing section 21 (Fig. and an outer tubular extension 06. A tube or pipe I51 is seated within extension 66, providing a pair of concentric passages therein. The inner end of member 61 terminates adjacent radial pa.

sages 68 in enlargement 05, and the annular passage 1I formed between extension 66' and member 61 communicates, at its inner end, with radial passages 12 in enlargement 65. Themember 61 forms the inlet for the coolant, whereas passage 1I forms the outlet therefore. Through the medium of suitable coupling means, such as a rotating union (not shown), the inlet and outlet communicate with a suitable coolant circulating system of the required capacity.

The cooling circuit for the secondary may be traced as follows. Coolant entering through member 61 flows into radial passages 68, and through insulating sleeves 13 into a dual inlet and outlet manifold 10. From manifold 10, the coolant flows through nipples 14 and 16 into interrupted annular tubes 11 and 18 seated in recesses 19 (Fig. 5) in casing section 21, each nipple being connected to one end of its corresponding interrupted annular tube. Also from the inlet section of manifold coolant flows through, connections 81, 81 secured in insulating nipplesv 82 in the ring gear 3!. Nipples 82 communicate with passages 83 extending longitudinally through the casing sections and connected, by conduits 84, 84, to interrupted annular tubes 8 .5, 81 seated in recesses in casing section 28.

The opposite ends of tubes 11 and 18 are connected by fittings BI, 92 to the outlet sectionof manifold 10. Similarly, an arrangement similar to the inlet connections, and including conduits 36to passages 41, 48 and 49 in cap 45. The coolantreturns from cap 45 through longitudinal passages 42 inmember 36 communicating with passage 41, and longitudinal passages 43 in member 31 communicating with passage 49. The inner ends of passages 42 are aligned with passages, I03v in casing section 21 which communicate with an annular passage I04 in the inner face of enlargement 65 as best seen in Fig. 5. Similarly, passages 43 communicate through passage I06 in section 28 and passage I01 in section 21. with an annular passage I08 (Fig. 5) in the inner faceof enlargement 65. Referring to Figs.

1 andZ, connections including a valve I II and an insulating sleeve I I2 connect annular passages 504 and I08 to passage H, from which thecoolant exits as described.

The primary winding 30 is mounted, for example in insulated relation Within the toroidal cavity formed by easing sections 21 and 28. The particular primary Winding illustrated includes four (4) sections, each extending for substantially one-quarter of the length of the secondary cas-- ing sections. Each section includes a toroidal tubular copper coil embracing the magnet core 35. The latter is secured in the casing sections by bolted brackets H3. The electrical circuit connections of the primary winding will be described more fully hereinafter.

Circulation of coolant through the primary winding is effected in the following manner. A connection I I4 and an insulating sleeve II5 connect passages 68 to an annular tubular maninipples I2'I eachconnected toone end of a primary coil section. The opposite end of each coil section is connected to a nipple I22 which in turn is connected to a thermostat I 20. Thermostat I20 isconnected, by a connection I23, to an outerannular tubular manifold I24 supported in a bracket I26. on shield II8. A connection I21, as best. seen in Figs. .1, 2 and" 6, interconnects manifold I24 and one of the outlet passages 12, for return flow of the coolant. The brackets I26 are made of insulating material. Thus, the coolant. is delivered to inlet manifold I I6 from whichit flows, in parallel, through the four (4) primary coil sections, and from the opposite en of each section to the outlet manifold I24 for delivery, through connection I21, to an outlet passage 12.

The current supply to the primary winding includes a commutator arrangement having sta-' tionary brushes engaging commutator rings ro-. tatable with the. transformer assembly. The control circuits for the thermostats 15 and I20 also include a commutator arrangement including fixed rings. and brush assemblies which are rotatable with the transformer.

The stationary part of .each commutator assembly is supported uponaa vertical post I30 which is precisely positioned so as to be in exact alignment with the vertical movement of the transformer assembly. Referring to Fig. 4, st

connected in series with each other.

ace 0,151

has spaced arms I32 secured at their outer ends to an annular insulating plate I35 embracing an insulating sleeve I33 on member 66. Plate I35 supports the brush assembly by means of bolts I34 extending through insulating sleeves I36 and connected to the outer brush ring I31.

Brush ring I31, as well as an inner brush ring I38 concentric therewith, are supported within an insulated holder I40, with the inner brush ring I38 embracing sleeve I33. Current is conducted from a suitable source through conductors MI and I42 secured to terminals I43 and I44, respectively, these terminals being mounted through plate I35 and having their inner ends conductively secured in rings I31 and I38 respectively.

Outer brush ring I31 supports three (3) brushes I45 which are spring biased inwardly by brush spring assemblies I46. Similarly, ring I38 supports three (3) brushes I50 which are spring biased inwardly by brush spring assemblies I41. Holder I40 carries a pair of rings I48 on its external periphery.

Brushes I45 and I50 conductively engage commutator rings I55 and I00, respectively, which are mounted in a ring holder II of insulating material. This holder is secured to rotate with the transformer assembly, being mounted on the inner end or manifold member 06. The four (4) primary winding sections are For this purpose, a terminal I50 is connected to ring I55 and has a connector I51 leading to one end of the first primary winding section, being electrically connected through the coolant inlet thereto. The other end of the first primary winding section is connected to the adjacent end of the next primary winding section by a conductor I58 leading from the coolant outlet of one section to the coolant inlet of the other section.

Similarly, conductors I59, I59 connect the other sections in series to the first two (2) sections. The end of the last section adjacent the leading end of the first section is connected by a conductor I6I to a terminal I62 secured to the ring I60. Thereby, the current flows from leader conductor I4I through the brush and ring arrangement to one end of the primary winding, and from the other end thereof, through the other commutator ring and its brushes to the lead or conductor I42.

To prevent coolant entering and affecting the brush and ring assembly, a deflector is disposed in embracing relation with such assembly separating the latter from the coolant connections. The deflector assembly includes brackets I65 secured to holder I5I and supporting shield I I8 in substantially parallel relation to post I30. The deflector assembly supports the primary manifold arrangement by means of suitable clamps and bolts.

Brackets I65 act as supports for an insulating holder I having brushes I1I engaging rings I48. Brushes I1I are connected in the control circuit for the thermostats and I20, and the control circuit connection to the cooling control means is efiected through the brush and ring assembly I48, I1I through suitable conductors (not shown).

With the described arrangement, a relatively high voltage is applied through the brush and ring assembly to the primary winding and electrical energy is inductively transferred to the single turn secondary winding comprising the casing sections 21, 28 and their tubular extensions 38, 31. The welding circuit is completed through the electrodes I5 and 20 each secured to a different tubular extension. As stated, these electrodes can be firmly seated on the transformer by virtue of the tapered seat mounting and the nut 52. The coolant flow through the inlet manifold is distributed to the primary winding coils in parallel, to the tubular members 3B, 31, and through the casing sections 21, 28. Distribution to the primary winding is effected through the manifolds H6 and I24. The thermostats 15 and I20, are connected in series with each other to control the return of coolant flow through the transformer assembly in accordance with varying temperature conditions.

While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the invention principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

I claim:

1. In electric seam welding apparatus a welding circuit including a pair of concentric, substantially telescoped, electrically conductive cylindrical members secured together as a unit in insulated relation to each other; the inner mem her having a radial extension axially beyond one end of the outer member; said one end of the outer member having a frusto-conical surface forming a seat, tapering toward the outer end of the outer member, for a circular electrode arranged to engage one edge of the longitudinal seam to be welded; said extension having a frusto-conical surface forming a seat, tapering toward the outer end of the outer member, for a second electrode arranged to engage the other edge of the seam to be welded; means insulating said electrodes from each other; the two frustoconical surfaces being part of the same conical surface of revolution; means engaging the second electrode and operative to force both electrodes inwardly along said tapered seats to fit tightly thereon; bearing means supporting said members for rotation; and means connecting said members to a source of electric potential.

2. In electric seam welding apparatus, a welding circuit including a pair of concentric, sub stantially telescoped, elongated, electrically conductive cylindrical members secured together as a unit in insulated relation to each other and each having coolant passages therein; the inner member having a radial extension axially beyond one end of the outer member and formed with means establishing communication between the coolant passages in said members; said extension being secured against rotation relative to said inner member; said one end of the outer member having a frusto-conical surface forming a seat, tapering toward the outer end of the outer member, for a circular electrode arranged to engage one edge of the longitudinal seam to be welded; said extension having a frusto-conical surface forming a seat, tapering toward the outer end of the outer member, for a second electrode arranged to engage the other edge of the seam to be welded; the two frusto-conical surfaces being part of the same conical surface of revolution; means insulating said electrodes from each other; means mounted for axial movement along said extension and engaging the outer surface of the second electrode and operative to force both electrodes inwardly along said tapered seats to fit tightly thereon; bearing means supporting said members for rotation; and means connecting the mn e n spmmmembe soa our es: le t ic n jt tia l 3, In electric seam welding annaratus; ameld ing circuitincluding;a pair ofconce'ntrio, substantiallytelescODd; elongated, electrically con; ductive cylindrical members secured together as a unltg'in insulated relation to eachother; the: inner memberhaving a radial extension secured" theretogaxially beyondpneendfof the outer merne ber; saidvone. end of the outer member being pro ,-v vided with i a, frustoeconical surface forming a seat, taperingtoward the outer end 0f the outer:

member, for a} circular electrode arranged to engage one, edge of the, longitudinal searn to he o l ed; ai xtension havin a r t onical surface Iorminga SeatQ, tapering; toward the outer end of the outerl mernber, for afsecond electrode 5 arranged to, engage the other edge of the. seam to g be welded; the Q two frustoconical surfaces being part of the. same conical surface of revolu;

tion; means insulating said electrodes frorn each other; means engaging the second electrq e and operative to force, both electrodes inwardlyalong said tapered seats to ,fit tightly thereon; bearing adjacent frusto-conical elements having their conical surfaces formed as part of a single conical surface of revolution to provide tapered elec trode seats; means insulating said elements from 10. V e. v

' ing transformer; including a, secondarywinding engageable with one fofsaid electrode seats,- the electrode seatingsurtaces forming part of th ef same conical suri' ace of revolution; {means operable to force said unit imvardlyalongsaid electrode ,seats to fittightly thereon;

5. In electric gseam welding --apparatus; a weld having its terminals formed as concentric; axially adjacent frusto conicalf elements T having their conical surfaces for ned as part oi a single conical 1 suriace of revolution to provide tapered electrode seats; means insulating" said-elementsfro1n each other; an electrode unit, comprising a pain of rotary; electrodes and an insulating disk secured m together concentrically asa unit with the disk? interposed between the electrodes eachelectrode; having a frusto conical seating surface engage; able with one {of said electrode seats, the electrode, seating surfacesformingjpartof the same con lcal surfaces of revolution; means, operable 1 to orcesa d un t nw rd yf vne a d de. ea

References Cited in the file of 1 this-patent UNITED, sTA rns PATENTS.

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1,811,886. Hunter June 30-; 1931; 2,284,315 Yoder May 26,: 1942,; 

